2. Introduction
Mutations are defined as sudden heritable
changes in the genetic material of an organism
and in turn in its characters that are not derived
from genetic segregation or recombination (Van
Harten, 1998).
They can result in deletion, inversion and
translocation of certain portions in the
chromosomes, which can result in the changed
expression of a trait due to the interaction of
alleles within or without the locus, sometimes the
effects revert back or can be heritable.
3. The term mutation breeding was coined to refer
to the deliberate induction and development of
mutant lines for crop improvement.
The term has also been used in a wider sense to
include the exploitation of natural as well as
spontaneous mutants, and in the development of
any variety possessing a known mutation from
whatever source.
4. Most of the fruit crops are highly heterozygous.
However, heterozygosity is one of the advantages
when it comes to mutation. In highly
heterozygous crops wherein there is a need for
improvement in a single trait, mutations have
been of great use.
5. In contrast, induced mutations change only one or a
few specific traits of an elite cultivar, and can
contribute to fruit improvement without upsetting
neither the requirements of the fruit industry nor the
consumers.
In fruit crops, mutagenesis has already been used
to introduce many useful traits affecting plant size,
blooming time and fruit ripening, fruit color, self-
compatibility, self-thinning, and resistance to
pathogens
( Sanada
and Amano, 1998)
6. Types of mutation
Spontaneous mutation
Mutation occur in natural populations.
Spontaneously arising mutations are very rare
and random events in terms of the time of their
occurrence and the gene in which they occur.
7. Some cultivars can have unstable phenotypes,
that are found in a portion of the plant , like whole
branches, having different characteristics- Bud
sports
When these branches (bud sports) are
vegetatively propagated, the new phenotype is
generally maintained leading to a new variety.
It often exhibit only one phenotypic character
different from the parent
(Marcotrigiano 1997)
8. When a mutation ( genic, chromosomal, genomic)
arises in a cell within a shoot apical meristem of a
bud, the mutated cell propagates mitotically and
produces a mutated sector (sectorial or mericlinal
chimera) (D' amato 1977).
Compared with conventional hybridization
breeding, bud sport is a consequence of genetic
variation of somatic cells leading to the
occurrence of qualitative and quantitative
phenotypic alteration in plants, which can be
observed in many vegetatively propagating plants
including grapes (Liu et al., 2007).
9. Chimeras
Mericlinal Chimera: mutation occurs in one
layer and along the side of the apex. Only a
section of one of the layers is mutated. Mericlinal
chimeras are not stable.
Periclinal chimera : a mutation occurs in one (or
more) layer at the top of the apex. The entire
layer is mutated.
Sectorial Chimera: A mutation occurs in multiple
layers at the top of the apex, an entire section of
the plant is mutated. They are stable to very
stable, and comprise the most common type of
chimeras in horticulture.
11. Induced mutation
Agents of artificial mutations are called mutagens.
They are generally grouped into two broad
categories, namely chemical mutagens and
physical mutagens (Mba et al., 2010).
Mutagenesis can be performed with all types of
planting materials, e.g. whole plants, usually
seedlings, seeds, and in vitro cultured cells.
12.
13.
14. In the case of seed propagated crops like
papaya, chemical mutagens can be utilized to
bring about changes.
Work carried out in papaya with induced mutation
using gamma irradiation has resulted in the
development of a dwarf dioecious variety Pusa
Nanha .
(Mansha Ram and
Srivastava, 1984)
15. Radiation and other chemical mutagens such as
E.M.S (Ethyl Methane Sulphonate) and D.E.S.
(Diethyl Sulphate) induce a much intensive
mutation than other chemical mutagens in most
of the crops.
(Hildering et
al., 1965)
EMS has proved to be one of the most effective
chemicals.
16. Dosage
LD50 is the dose of mutagen that kills 50% of the
treated individuals of treatment depends on
intensity of radiations or concentration of
chemical mutagens.
Optimum mutagen dose is one, which produces
maximum frequency of mutations and causes the
minimum killing.
17. Plant materials for treatment
Seeds, pollen grains, buds/cuttings or complete plant
can be used for mutagenesis.
Depends on whether the crop is sexually or
asexually propagated and type of mutagen
Mutation originates in a single cell, it has to manifest
to the whole plant, so the target material must be
meristematic tissues.
Although nearly all the parts of a plant can be
induced to develop meristematic tissue, shoot tip
meristems in leaf buds or in seeds are typically
targets for mutation.
18. Procedure for development of mutants in
sexually propagated fruit Crops
In sexually propagated crops, seeds are commonly
used.
From treated seeds M1 generation is developed.
In M1 generation large number of plants are grown
with wider spacing. Dominant mutations are
recorded if any (generally mutations are recessive
and do not express in M1). Chlorophyll sectors and
fertility are recorded.
M1 plants are selfed and their seed is harvested
separately.
In M2 seed obtained from M1 is sown in wide
spacing, selected mutants are selfed, Oligogenic
mutations are detected in M2 and are harvested
19. M3 progeny is raised from selected M2 and
evaluated for homozygosity.
Selected homozygous M3 progenies are bulked
together to conduct yield trials in M4.
M4 progenies are raised in replicated trials using
local check for comparison.
From M5-M9 generations, selected lines are tested
in multiplication coordinated trials.
20.
21. Vegetatively propagated crops
In vegetatively propagated crops, mutations are
expressed in the form of chimeras. The chimera
refers to genetically different tissue in an
individual.
For eg. “variegated” plant where different regions
of the leaf are yellow or white due to lack of
chlorophyll synthesis, i.e. these are chlorophyll
mutants.
Thornless blackberries are chimeras where the
L-I epidermis lacks the ability to produce thorns.
Some fruits have sweet and sour regions of flesh,
which may be a chimera.
22. Works in mutation breeding
Sutarto et al., (2009) found that bud woods of
mandarin cv. So E and Garut and pummelo
cv. Nambangan when irradiated with gamma
rays @ 20Gy gave seedless fruits, with yellow
skin colour, green pulp colour and thick
endocarp/
Zhao et al., (2014) reported an Early-ripening
Benitaka‟ grape, a bud sport of the „Benitaka‟
(Vitis vinifera) cultivar that exhibits a marked
difference in sugar and anthocyanin
accumulation in ripening fruit arises from a
spontaneous mutation.
23. Fernandez et al., (2006) identified a mutant in
grapevine (Vitis vinifera) named as fleshless berry
(flb) that reduced by 20 times the weight of the
pericarp at ripening without any effect on fertility
or seed size and number.
The flb mutation strongly impaired division and
differentiation of the most vacuolated cells in the
inner mesocarp.
The timing of ripening was not altered by the
mutation although the accumulation of malic acid
in the green stage was noticeably reduced while
sucrose content increased during ripening. The
mutation segregated as a single dominant locus.
24. Hensz (1971) developed the seedless ‘Star Ruby’
grapefruit through irradiation of seed of the seedy
‘Hudson’ by thermal neutrons.
Hearn (1984) produced seedless strains of
‘Pineapple’ orange and ‘Duncan’ and ‘Foster’
grapefruit from γ-ray irradiation of seeds.
Chen et al., (1991) were able to produce
seedless strains of ‘Jin Cheng’ orange through γ-
irradiation of seeds, however, chromosomal
aberrations were observed in these strains.
25. Mutation induction in banana has been carried
out by subjecting of shoot tips to mutagen
followed by regenerating of treated shoot tips
(Predieri, 2001).
Bhagwat and Duncan (1997) also used chemical
mutagens in banana (Musa spp. AAA group) to
produce variants displaying resistance against
fusarium wilt (Fusarium oxysporum f. sp.
cubense). They determined 200 mM of EMS for
30 min as an optimal dose and duration treatment
30. Induction of mutation in vitro
Somsri et al., (2009), showed successful
induction of mutation in vitro through gamma
irradiation using both chronic and acute
procedures resulting in improvement of quality
characteristics viz., seedlessness of fruit in
tangerine (C.reticulata) and pummelo (C.
grandis).
31. Induction of mutation in vitro
Zamir et al, (2009), studied in vitro mutagenesis
followed by micropropagation via axillary bud
proliferation in shoot tips of guava (Psidium
guajava) cultivar Safeda.
In the shoot tips irradiated with 90 Gy gamma
rays, shoot proliferation was observed after 7
weeks of culture initiation. The bud woods of
guava cv. Safeda were more radiosensitive than
seeds.
32. Detection of mutation in fruit
crops
Single Nucleotide Polymorphisms (SNPs) are
increasingly used as DNA markers because
techniques are becoming more widespread, cost
effective and automated and the genome
sequence information of major crops are
becoming increasingly available for use.
Since many naturally occurring mutations are
single nucleotide polymorphisms (SNPs), various
technologies have been developed for SNP
detection, most of which are also useful for the
detection of small insertion/deletions (indels).
33. LIMITATIONS
The process is generally random and
unpredictable.
Useful mutants are rare and predominantly
recessive.
Mutants can have strong negative pleiotropic
effects on other traits.
Health risks: handling, chemical mutagens;
radiations, fast neutrons treatments.
Most mutants are of no use to breeding even if a
large number of mutants can be produced.
Field trialing and germplasm storage can be
expensive and require a lot of space and careful
management if large mutant populations are
handled.
36. The objective of this research was to examine the
effect of different doses of γ-irradiation on the
growth of mango (Mangifera indica L.) grafted
material. The experiment was conducted at
Subang Experimental Field, West Java, from May
to December 2009.
Design :Randomized Complete Block Design
No. of treatments :5
No. of replications:3,
each treatment consisted of 40 scions.
37. The treatments were doses of γ-rays irradiation,
consist of:
T1 0 (non-irradiated as control)
T2 20 Gy,
T3 40 Gy,
T4 60 Gy, and
T5 80 Gy.
Mango scions of cv. ‘Arumanis’ were irradiated
with γ-rays at CRDIRT-BATAN Jakarta and then
grafted on one year old of mango rootstocks at
Subang Experimental Field
38.
39.
40. Result
Mango grafted materials that could grow were
obtained from 0-40 Gy γ- irradiation. Doses of γ-
irradiation beyond 60 Gy was lethal to mango cv.
‘Arumanis’.
41. Title: Studies on mutation breeding in mandarin
variety Kinnow
Author :Harinder Singh Rattanpal*, Gurteg Singh
and Monika Gupta
42. The study was undertaken to generate variability in
Kinnow (Citrus nobilis Lour × C. deliciosa Tenora)
using gamma radiation.
Four hundred buds of Kinnow were irradiated at 30
Gy and budded on rough lemon rootstock in February
2007.
The resulting 188 MV1 plants were planted in the field
in October 2009 and observations in the present trial
were recorded from 2015 to 2018.
Among the 188 MV1 plants, eleven Kinnow mutants
(seven solid mutant trees and four mutant branches)
having average seed number less than eight were
identified, showing distinct desirable characters and
were compared in detail with parent variety Kinnow.
43.
44.
45.
46.
47. Result
Huge variability was observed in the mutant
population for many traits of commercial
significance. In the present trial, selection was
focused on low seed number.
One of these mutants, mutant-1 was released as
new variety named ‘PAU Kinnow-1’ for general
cultivation in Punjab, India.
